Chlorine (Cl2) has long been used in municipal, industrial, and wastewater treatment, because of its capacity to kill most pathogenic bacteria. However, chlorine in the feed water can quickly damage membranes in reverse osmosis (RO) systems.
What is the effect of chlorine on RO Membranes?
Chlorine damage to the membrane can result in decreased salt rejection and poor-quality permeate, requiring expensive membrane replacement and downtime.
If there is chlorine in the feed water, it is commonly neutralized with a sodium sulphite solution, a carbon bed, or a combination of the two. Both techniques are effective, but operators who utilize these technologies and check their chlorine levels may be astonished to learn that their RO membranes are still affected by chlorine.
The acceptable limit of free chlorine to avoid membrane damage
Chlorine is routinely used to disinfect drinkable water, with a residual chlorine content of around 0.5 mg/L. Fouling of water intake lines, heat exchangers, sand filters, and other components of a water treatment system can be avoided by maintaining a free Cl2 residual of (0.5-1.0 mg/L).
The more chlorine in the supply, the better and longer the chemical can protect the system from pollution. High quantities of chlorine, on the other hand, make the water smell and taste terrible, discouraging people from drinking it.
Chlorine levels at the point where the customer receives water should be between 0.2 and 0.5 mg/l for normal home use. The greater level will be near the disinfection point, and the lower level will be at the supply network's remote reaches.
A chorination check list
• Chlorine disinfection requires at least 30 minutes of contact time with water. After any other treatment, and before storage and usage, is the best time to apply chlorine.
• Never use chlorine before slow sand filtration or any other biological process since it will kill the bacteria that help with treatment, rendering it ineffective.
• Never directly add any solid form of chlorine to a water source since it will not mix or dissolve. Always start by making a paste with the chlorine compound and a little water.
• Disinfection is merely one line of defence in the fight against disease. Every effort should be made to prevent contamination of water sources and subsequent contamination during collection and storage.
• The proper technique for applying a disinfectant to water should be followed, and water supplies should be checked on a regular basis to verify that they are bacteria-free. People may be misled into believing that the water is safe to drink when it is actually dangerous.
Access to clean water for human use is becoming increasingly important as the world's population grows!
Membrane biofouling, on the other hand, is the most serious problem that RO plants confront, necessitating constant cleaning or membrane replacement on a regular basis. Pre-treating water with chlorine to decrease biofouling is the most popular disinfection method.
Cl2's efficacy is determined by the amount of Cl2, the length of exposure, and the pH of the water. Despite its widespread use, chlorination has significant drawbacks, including the generation of disinfection by-products. As a result, our experts at Netsol Water Solutions use a precise chlorine percentage to avoid the drawbacks.
What else do we offer?
If you want to know more about the acceptable limit for chlorine in RO Plants, then you are at the right place!